pH problem again

When I was using Instant Ocean, my freshly mixed RO/DI water parameters are:

pH 8.4-8.5
dKH at 13 (KH 260ppm, Alkalinity 4.64 meq/l)

Now that I switched to Oceanic, my freshly mixed (and with powerhead mixing it for 1-2 days):

pH is 7.9 (at 78F sg 1.0245)
dKH at 12 (KH 240ppm, Alkalinity 4.28 meq/l)

What's a good additive to increase the pH?

I don't know if this helps you out at all, but I remember reading in one of the technical articles that sometimes low pH is a result of poor air circulation rather than just not using the right additives. Something about how having ripples at the top of your tank is not enough, especially if you have stale air sitting there; so by setting up a fan or by placing your tank in an area with good circulation, you can improve your pH levels. However, this may be super common knowledge and you may know that already, so disregard this paragraph if you do.

Not having a lot of experience with different products myself, I've been using this Reef Pure Marine pH Buffer stuff from WM Research that has been working really well in my tank. My LFS was telling me that it's good because it used less heavy metals or something; could've been blowing smoke up my , but it seems to be working well.

dissolved oxygen in the water does affect PH, correct.

try mixing the two salts, IO has high alk low calcium and oceanic is the opposite, together they're amazing..... the "Miracle Mix". That's what i did on my last tank and it was great!

I took his comment to mean something else -- a build up of carbon dioxide also causes low pH.

Either way, point made, I believe

It's for water that's just mixed with salt, not in the tank yet. When I was using Instant Ocean, I was able to lower the pH a little bit by using a power head. Now that the pH is little too low with Oceanic, the power head trick doesn't help any more. That's why I want to see if there are any additive that you use to increase the pH.

Theres not any that I know of that will raise the PH without raising the alkalinity too.

Are you making sure to check the PH at the same time of day as well? The lighting will also affect PH quite a bit (why a lot of people run fuges on opposite schedules). What are your CA, MG, and dKH levels?

I could be wrong but I believe using pH 8.2 by API will stabilize you. I use it every so often but I can't find anything on the container about what it will do to your other parameters. Seems to work well though, and my reef doesn't seem to mind it.

If your looking for something that is basically free, you can use some baked baking soda. I baked some in the oven at 350 for a couple of hours and then I stored it in a little container for later use as needed. For my tank I mix a teaspoon up in a cup of tank water and pour it in my sump return section.

I've been having a slightly low ph problem for awhile. I added a mesh bag about with some crushed coral to my sump. After about a week in the sump ph is finally staying over 8, I'd assume it will get better next week